1. Field of the Invention
The present invention relates to an automatic performance apparatus, and more particularly to an automatic performance apparatus which plays an automatic performance based on performance data stored in a memory.
2. Prior Art
As a first conventional automatic performance apparatus, the apparatus as disclosed in Japanese Utility Model Laid-Open Publication No. 62-2096 has been well known. This first apparatus displays used capacity of memory by address number.
This first apparatus is advantageous in recording the performance data in the memory because it can visually display remaining capacity of memory. However, since quantity of performance data stored in the memory depends on a kind of musical tune, it is impossible to catch a progressing position of tune when the performance data are read from the memory.
Meanwhile, a second conventional automatic performance apparatus as disclosed in Japanese Patent Laid-Open Publication No. 62-175796 provides a search controller for changing the progressing position of automatic performance to the desirable position. When the search controller is revolved in left or right direction, an address count value designates a reading address of memory by the speed corresponding to its revolving position (i.e., by the speed which is faster than the normal performance speed). By incrementing or decrementing such address count value, musical tones are sequentially generated by a rate which is faster than the normal rate, so that the reading positions of performance data are changed.
In this second conventional automatic performance apparatus, the speed for incrementing or decrementing the address count value is set at the speed by which the musical tones are sequentially generated. For this reason, the second conventional automatic performance apparatus is disadvantageous in that it is impossible to change the reading position of performance data to the desirable position within a short time.
On the contrary, it is possible to set the speed for incrementing or decrementing the address count value at the speed by which the musical tones cannot be sequentially generated, in other words, a system clock speed of digital system, a processing speed of microcomputer or the like. In such case, the reading position of performance data is also sequentially changed as long as the search controller is revolved, so that the change in the reading position of performance data becomes too large as compared to the case where reading position of performance data is changed in synchronism with the revolving speed of the search controller. Therefore, as similar to the foregoing case, it is difficult to change the reading position of performance data to the desirable position.